Recently, it has been proposed that Reissert compounds be synthesized to develop novel heterocyclic polymers for high performance applications (see H. W. Gibson et al., Amer. Chem. Soc., Polymer Preprints, 29(1), 154, 1988). Bis (Reissert compounds) have been synthesized in excellent yields by the use of a trimethylsilyl cyanide reagent and can be used to develop such polymers (see A. Pandya et al., Amer. Chem. Soc., Polymer Preprints, 30(1), 206, 1989). Several novel 4,4'-coupled bis-isoquinolines have also been synthesized (see H. W. Gibson et al., Amer. Chem. Soc., Polymer Preprints, 30(1), 208, 1989).
Polyheterocyclic polymers, in general, are known to have good thermal and physical properties. Thus, polyquinolines, polyquinoxalines, polybenzoxazoles, polybenzothiazoles, and polybenzimidazoles have been prepared as "rigid rod" systems with high thermal transition temperatures and good high temperature mechanical properties (see Encycl. Polymer Science and Engineering, Second Edition, Vol. 7, pp. 639-665) Polybenzimidazoles, however, demand special processing conditions because of low solubility The benzimidazole ring is formed in the polymerization process and the product polymer must be processed from the reaction mixture, typically polyphosphoric acid (see Encycl. of Polymer Science and
Engineering, Second Edition, Vol. 11, pp. 572-601).
The instant process allows for a method for producing polymers by using benzimidazole itself as a monomer. The product polymers possess several advantageous features: (1) they are soluble; (2) they are chemically modifiable for the production of poly(keto/amides) and poly(ester/amides); and (3) copolymerization with polyamide and polyester monomers allows property enhancement of these materials by the presence of the benzimidazole nucleus.